Pure rotational spectrum of gold monoxide (AuO) in the X2Π3/2 state

A data-driven approach to determine dipole moments of diatomic molecules

We present a data-driven approach for the prediction of the electric dipole moment of diatomic molecules, which is one of the most relevant molecular properties. In particular, we apply Gaussian process regression to a novel dataset to show that dipole moments of diatomic molecules can be learned, and hence predicted, with a relative error ⪅5%. The dataset contains the dipole moment of 162 diatomic molecules, the most exhaustive and unbiased dataset of dipole moments up to date. Our findings show that the dipole moment of diatomic molecules depends on atomic properties of the constituents atoms: electron affinity and ionization potential, as well as on (a feature related to) the first derivative of the electronic kinetic energy at the equilibrium distance.

Gold with +4 oxidation state compounds: mass spectrometric and theoretical characterization of AuO2+

Using an ab initio methodology and mass spectrometric study we identify AuO²⁺ as a metastable species in the gas phase.

The electric dipole moments in the ground states of gold oxide, AuO, and gold sulfide, AuS

The B²Σ^- - X²Π_3/2(0,0) bands of a cold molecular beam sample of gold monoxide, AuO, and gold monosulfide, AuS, have been recorded at high resolution both field free and in the presence of a static electric field. The observed electric field induced splittings and shifts were analyzed to produce permanent electric dipole moments, μ→_el, of 2.94±0.06 D and 2.22±0.05 D for the X²Π_3/2(v = 0) states of AuO and AuS, respectively. A molecular orbital correlation diagram is used to rationalize the trend in ground state μ→_el values for AuX (X = F, Cl, O, and S) molecules. The experimentally determined μ→_el are compared to those computed at the coupled-cluster singles and doubles (CCSD) level augmented with a perturbative inclusion of triple excitations (CCSD(T)) level of theory.

The Electronic Spectrum of AuO: A Combined Theoretical and Experimental Study

The near-infrared electronic spectrum of AuO(1) has been re-examined in light of the new microwave data on the v = 0 and v = 1 vibrations of the X(2)Pi(3/2) state of AuO. The two observed bands in the spectrum, with red-degraded bandheads located at 10726 and 10665 cm(-1), have been reanalyzed. New theoretical work on AuO clarifies the electronic structure, and the bands in the infrared are now assigned as the (0,1) and (1,2) bands of the a(4)Sigma(-)(3/2) - X(2)Pi(3/2) transition, respectively.

The low-lying electronic states of nickel cyanide and isocyanide: A theoretical investigation

At different levels of coupled cluster theory optimum structures, energetics, and harmonic vibrational frequencies for several low-lying doublet and quartet electronic states of linear NiCN and NiNC were studied using four contracted Gaussian basis sets, ranging from Ni[6s5p4d2f], CN[4s3p2d] to Ni[8s7p5d3f2g1h], CN[5s4p3d2f1g]. The most reliable predictions were obtained with a relativistic Douglas-Kroll restricted open-shell-based coupled cluster method including singles, doubles, and perturbative triple excitations [DK-R/UCCSD(T)]. This level of theory was used in conjunction with correlation-consistent polarized valence Douglas-Kroll recontracted quadruple-zeta basis sets (cc-pVQZDK). The energetic ordering of the electronic states of NiCN is predicted to be 2delta < 2sigma+ < 2pi < 4delta < 4pi and that of NiNC is 2delta approximately 2sigma+ < 2pi < 4delta < 4pi < 4sigma-. Our theoretical investigation supports the assignment of the ground-state term symbol, the Ni-C stretching frequency, and the bending frequency for the ground electronic state of NiCN by Kingston et al. [J. Mol. Spectrosc. 215, 106 (2002)] and by Sheridan and Ziurys [J. Chem. Phys. 118, 6370 (2003)]. The predicted structure of the 2delta ground state of NiCN, r(e)(Ni-C) = 1.822 angstroms and r(e)(C-N) = 1.167 angstroms, at DK-R/UCCSD(T)/cc-pVQZDK shows excellent agreement with the experimentally determined Ni-C bond length of 1.826 A and less satisfactory agreement for the C-N bond length of 1.153 angstroms [J. Chem. Phys. 118, 6370 (2003)]. It is also concluded that the metal-to-ligand pi back donation is weak or negligible. Additionally, we found that on the 2delta surface the linear cyanide isomer lies lower in energy than the linear isocyanide isomer by 12.2 kcal mol(-1).

Infrared Spectra and Structures of the Coinage Metal Dihydroxide Molecules

Laser-ablated Cu, Ag, and Au atoms react with H2O2 and with H2 + O2 molecules during condensation in excess argon to give four new IR absorptions in each system (O-H stretch, M-O-H bend, O-M-O stretch, and M-O-H deformation modes) that are due to the coinage metal M(OH)2 dihydroxide molecules. Isotopic substitution (D2O2, 18O2, 16O18O, D2, and HD) and comparison with frequencies computed by DFT verify these assignments. The calculations converge to 2B(g) ground electronic state structures with C2h symmetry, 111-117 degrees M-O-H bond angles, and substantial covalent character for these new metal dihydroxide molecules, particularly for Au(OH)2. This is probably due to the high electron affinity of gold owing to the effect of relativity.

Infrared spectrum and structure of the gold dihydroxide molecule

Reactions of laser-ablated gold atoms with H2O2 and H2+O2 mixtures give four new infrared absorptions, which match the four most intense vibrational frequencies calculated for Au(OH)2 using density functional theory; the calculations find a C2h structure and substantial covalent bonding character for the Au(OH)2 molecule, which is probably due to the high electron affinity of gold.